I'm attempting to replace the chainrings on my Cannondale Road tandem. The crankset is a Truvativ Elita Tandem (52-39 10 speed big/middle ring). The new rings are Shimano 6603 52-39 rings.
I swapped out the rings without issue. I've also replaced the cassette and drive chain.
The chain runs fine in the big ring.
The problem shows up with the chain on the middle ring and on the three smallest cogs of the cassette. In those gears, the chain skips frequently. It appears to try to jump up to the big ring, then falls back down, a couple of teeth back on the middle ring. It is skipping more than once per chain cycle, which I think rules out a problem with the chain.
Watching the chain closely it appears what is happening is that the chain is catching on the little shifting helper nubs on the inside of the big chainring.
It is not the derailleur causing the chain to shift. I've made sure the derailleur is not touching the chain. The same thing also happens on the bottom of the chainring if I backpedal.
Is there any reasons these rings would be a problem on this crankset? Any other things to try?